CONTRIBUTIONS TO PALiEONTOLOGY. 55 



EUOMPHALUS EBOEACENSIS (n.s.). 



Shell discoid. Volutions subrotund, the section somewhat pentahe- 

 dral, the upper side a little flattened, regularly curving on the 

 inner side, narrowed and flattened on the lower side; the dorsal 

 side presenting two narrow flattened faces with an obtuse angle 

 between :• towards the aperture, the inner side becomes straight 

 and the lower side scarcely flattened. 



Surface marked by closely arranged lamellose strise, which are 

 crowded and fasciculate, giving a somewhat rough exterior. 



The entire form and character of this species are not determined ; the 

 specimen examined being imperfect. 



Geological formation and locality. In the shales of the Hamilton group 

 at Eighteen-mile creek in Erie county, and at York in Livingston co. N. Y. 



GENUS BELLEROPHON (Montfort). 

 BELLEBOPHON CURVILINEATUS (Conrad). /, / ;: '^-f 



Bellerophon curvilineatus : Conrad, Jour. Acad. Nat. ScienceSj Philadelphia, 1842, 



Yol.viii, pa. 269, pi. 16, f. 7. 



" Discoid : volutions exposed; back sharply carinated; surface with 

 " oblique arched strise." 



This species, cited by Mr. Conrad as occurring in the Onondaga lime- 

 stone, is more abundant in the Schoharie grit, though in this rock it rarely 

 preserves the shell. The shell is discoidal ; the volutions four or five, com- 

 pressed and sharply carinated on the back, each one embracing about half 

 the width of the preceding one, the last one not more ventricose than the 

 preceding, and bending almost rectangularly at the umbilical edge. Aper- 

 ture triangular, acute at the anterior margin, which is deeply sinuate ; the 

 curvature of the peristome from the umbilical side receding about one quar- 

 ter of a volution to the dorsal line. The inner margins of all the volutions 

 are exposed in the cavity of the umbilicus. Surface marked by fine striaa of 

 growth, which are slightly fasciculate and follow the curvature of the aper- 

 ture, making a retral curve of about one quarter of a volution. The dorsum 

 is sharply carinate. 



The casts of this species are angular on the back, showing a wide um- 

 bilicus. 



This species has somewhat the form and proportions of the B. duhia of 

 D'Orbigny ; but the umbilicus is proportionally larger, and the outer 

 volution less rapidly widening towards the aperture. 



Geological formation and locality. In the Onondaga limestone and 

 Schoharie grit, at Schoharie and the Helderberg mountains. 

 1861.] 



